We do mix those. Occasion tally. A major afrlgs for a classic TV show. Can you believe "The Brady bunch" premieres 50 years ago. That's incredible. Wow, right? Now the Brady kids are back home in that original house. They're redoing it and bringing it to '70s style and glory and Lara was right there for it all. Hey, Lara. Reporter: Good morning, guys. I have a question. What do you get when you take the six original Brady kid, eight hosts from different HGTV shows and one massive amazing undertaking, I present to you a very Brady -- ren nation here's a story of a lovely lady Reporter: "The Brady bunch" is back. It's been 50 years since Greg, Marcia, Peter, Jan, Bobby and ndy made their way into our hearts and homes. Became the Brady bunch the Brady bunch Reporter: All six reuniting for the first time in decades. Hi, honey, I'm home. Reporter: Rolling up their sleeves to help renovate their TV home. Hg-tv bought the house for $3.5 million in 2018 then enlisted eight of its hosts including me for a transformation. One, two, three. Reporter: That is nothing short of priceless. Working alongside HGTV's Jasmine Roth and Barry Williams we were in charge of Greg's groovy attic. I'm in big, big number art and eve plumb helped me re-create Alice's bedroom. Why was it important. Alice was a selfless character in the show. We saw some of her life but it's really nice to think that we could pamper Alice a little bit. Reporter: When the producers chose this house to become the bradys' it was only for the exterior. Now the interior is an exact match. I thought it was impossible to pull this off. It's like traveling back in time. But traveling back in time and coming home. I think everybody really felt the genuine love. It is the definition of surreal. They created a home that we only have in our memory now because it was just a set. 50 years later in honor of your 50th anniversary, what do you want viewers to get out of this? That they'll get an experience of what this -- this home, this house represented, which is just that, getting along, communicating, trusting one another or in the works of Mike Brady, one for all, all for one. Reporter: That home becoming a reality -- Oh, my. An unbelievable seven months. When HGTV bought it it was a single story and ended right here. Meaning no second floor and no iconic staircase. Big problem. Our team adding over 2,000 square feet of space to the back of the house. To account for each room on the TV set including the second floor. I see the makings of the staircase. Reporter: Every furnishing meticulously matched. Come on out of there. Reporter: From old episodes. Oh. Anybody got three coins for the fountain? My grapes are here. How close did we get on the It's the horse. The horse. Nailed it. We're always walking from the kitchen into the living room for to the front door. Up the stairs. Or down the stairs. And we're at the dining room table and the horse is there. It's an anchor. It was strangely unsettling to be on the second floor in this house because our bedrooms were actually right outside that door. Because it was all on one floor in on the ground floor. Of the stage. Even outsourcing through fans to find rare items like this stuffed animal giraffe seen on almost every episode in the girls' bedroom. It will bring back classic memories like this. Oh, no. You know what mom said? She always says don't play ball in the house. Reporter: And from the inside to the outside our cameras capturing the final reveal of the backyard. Everything here feels so right. It's just crazy. Walking in and feeling like everything is staged by paramount because it was a home. And this is a real one now. I need to throw. Throw me the ball. Don't break my nose? Hey, you guys. Oh, my nose. In honor, the theme is complete. Spike the football. We did it. We did it. So now that the renovation is complete, what happens to the Brady house, you ask? HGTV says expect more fun in the year to come. You can watch "A very Brady renovation" on HGTV this coming September. Back to you in New York. We cannot wait for that. Lara, thank you. Sounds like so much fun. So much fun. She is right up in her element. I can't believe it's 50 years. It's incredible.

This transcript has been automatically generated and may not be 100% accurate.

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